Math Problem Statement

a rectangle whose length is 4 times of its width has the area of 44 cm2 . find the perimeter and the length of the diagonal of the rectangle . give your final answer in the radical form

Solution

Let's denote the width of the rectangle as ww. According to the problem, the length ll is 4 times the width, so:

l=4wl = 4w

The area AA of the rectangle is given as 44 cm², and the area of a rectangle is calculated as:

A=l×wA = l \times w

Substituting the values:

44=4w×w44 = 4w \times w

44=4w244 = 4w^2

To find ww, divide both sides by 4:

w2=444=11w^2 = \frac{44}{4} = 11

Now, take the square root of both sides:

w=11 cmw = \sqrt{11} \text{ cm}

Since l=4wl = 4w:

l=411 cml = 4\sqrt{11} \text{ cm}

Perimeter Calculation

The perimeter PP of a rectangle is calculated as:

P=2(l+w)P = 2(l + w)

Substituting the values of ll and ww:

P=2(411+11)=2(511)=1011 cmP = 2(4\sqrt{11} + \sqrt{11}) = 2(5\sqrt{11}) = 10\sqrt{11} \text{ cm}

Diagonal Length Calculation

The length of the diagonal dd of a rectangle can be found using the Pythagorean theorem:

d=l2+w2d = \sqrt{l^2 + w^2}

Substituting the values of ll and ww:

d=(411)2+(11)2d = \sqrt{(4\sqrt{11})^2 + (\sqrt{11})^2}

d=16×11+11=176+11=187 cmd = \sqrt{16 \times 11 + 11} = \sqrt{176 + 11} = \sqrt{187} \text{ cm}

Final Answers

  • The perimeter of the rectangle is 101110\sqrt{11} cm.
  • The length of the diagonal of the rectangle is 187\sqrt{187} cm.

Would you like more details or have any questions?


Here are 5 related questions for practice:

  1. If the area of a square is 44 cm², what would be its side length and perimeter?
  2. What is the area of a rectangle if its length and width are 2112\sqrt{11} cm and 11\sqrt{11} cm, respectively?
  3. How would the diagonal change if the width was doubled while keeping the length the same?
  4. What is the length of the diagonal of a rectangle whose sides are 7 cm and 24 cm?
  5. What is the perimeter of a rectangle whose length is twice its width and has an area of 72 cm²?

Tip: When solving geometric problems, always sketch a quick diagram to better visualize the relationships between the elements like length, width, and diagonal.

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Math Problem Analysis

Mathematical Concepts

Geometry
Rectangles
Radical Expressions
Pythagorean Theorem

Formulas

Area of a rectangle: A = l × w
Perimeter of a rectangle: P = 2(l + w)
Diagonal of a rectangle: d = √(l² + w²)

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 8-10